A manufacturing process of a semiconductor device includes various processes such as a lithography process, an etching process, and an ion implantation process. After each process is completed, and before the following process is started, a cleaning process and drying process for removing impurities and residues remaining on a surface of a wafer so as to clean the surface of the wafer are performed.
With microfabrication of a device, a problem of a resist pattern being collapsed due to a capillary action arises, when the resist pattern after the lithography process (exposure and development) is rinsed and dried. In order to solve this problem, there has been proposed a technique in which a surface of a resist pattern is made water repellant to reduce a capillary force acted between the resist pattern and a liquid developer as well as a rinsing pure water (e.g., JP-A 7-142349 (KOKAI)). According to this method, an organic substance is deposited on the surface of the resist pattern. However, this organic substance is removed in the etching process after the lithography process together with the resist pattern.
For example, in the wafer cleaning process after the lithography process, chemical used for the cleaning process of the surface of the wafer is supplied, and then, pure water is supplied to perform a rinsing process. After the rinsing process, the drying process is performed in which the pure water remaining on the surface of the wafer is removed to dry the same.
As the drying process, a spin drying is performed, for example, in which the wafer is rotated to remove the water content on the surface with centrifugal force. There arises a problem, during the drying process, that silicon is eluted to produce a drying stain called a watermark on the wafer, which reduces a yield. There arises a further problem that, during the drying process, the pattern on the wafer is collapsed due to the capillary force.
In recent years, there has been proposed a technique of drying a wafer by substituting the pure water on the wafer into IPA (isopropyl alcohol) with the use of IPA (e.g., specification of Japanese Patent No. 3866130). There has also been proposed a technique of using HFE (hydrofluoroether) having a surface tension lower than that of IPA. However, even by the drying methods described above, it is difficult to prevent the collapse of the micropattern on the wafer caused by the surface tension of liquid.